Hand Foot and Mouth Disease — SCE Dermatology MCQ

Correct answer: D — Coxsackievirus A16 (or Enterovirus A71)

Coxsackievirus A16 (or Enterovirus A71) is correct. Hand, foot and mouth disease is a classic enteroviral exanthem, most commonly caused by Coxsackievirus A16, with Enterovirus A71 accounting for a significant minority of cases and being associated with more severe or neurological disease. The clinical picture described, painful oral vesicles/ulcers plus a vesicular eruption on the palms and soles in a young adult with a nursery-attending child, is textbook for this faecal-oral and respiratory droplet spread infection, which is highly contagious in childcare settings. Nursery contact is the key epidemiological clue pointing away from the other vesicular dermatoses listed, since HFMD outbreaks cluster in exactly this setting. Why the other options are wrong: B. Varicella-zoster virus: causes chickenpox with a centripetal, crop-wise vesicular rash mainly on the trunk and face, not a palm-and-sole-predominant eruption with oral ulcers, and does not track with nursery HFMD outbreaks. A. Parvovirus B19: causes erythema infectiosum (slapped cheek syndrome) or a lacy reticular rash and arthropathy in adults, not oral vesicles or a palmoplantar vesicular eruption. C. Herpes simplex virus: causes grouped vesicles on an erythematous base, typically herpetic gingivostomatitis or genital/labial lesions, but does not classically produce a symmetrical palm and sole vesicular eruption alongside oral ulcers. E. Human papillomavirus: causes verrucae and warts through epidermal proliferation, an entirely different, non-vesicular, non-infectious-exanthem pathology. Key point: the combination of painful oral ulcers with a vesicular rash on the palms and soles, especially with a household contact at nursery, is diagnostic of hand, foot and mouth disease caused by Coxsackievirus A16 or Enterovirus A71.

Reference: NICE CKS, Hand, foot and mouth disease, August 2020, https://cks.nice.org.uk/topics/hand-foot-mouth-disease/